The mucosal membrane or tissue is a mucus-secreting membrane which lines all body cavities or passages that communicate with the exterior. While bioadhesion refers to the ability of certain synthetic and biological macromolecules and hydrocolloids to adhere to biological tissues, mucoadhesive compounds are capable of adhering to mucosal membranes (mucosal tissues) through a complex phenomenon, which in part depends upon the properties of compound, biological tissue, and the surrounding environment. Several factors have been found to contribute to a compound's bioadhesive capacity: the presence of functional groups able to form hydrogen bridges, the presence and strength of anionic charges, sufficient elasticity for the polymeric chains to interpenetrate the mucous layer, and high molecular weight. For this reason, most mucoadhesive compounds are polymeric.
Mucoadhesive drug delivery systems exploit the attraction between the mucus and polymeric drug carrier. They provide localization of the carriers within the specific site and prolonged residence time of the delivery devices. These greatly enhance the bioavailability of the drugs, especially in the case of peptide and protein delivery. Such systems have been used in dentistry, orthopedics, ophthalmology, and in surgical applications and recently with the emergence of controlled release systems for local release, such applications include also systems for release of drugs in the buccal or nasal cavity, and for intestinal or rectal administration.
Mucoadhesive vaginal formulations have also been disclosed for example by Gavini et al (Mucoadhesive vaginal tablets as veterinary delivery for the controlled release of an antimicrobial drug, acriflavone: AAPS PharmaSci 2002; 3(3) article 20) and C. Valenta (The use of mucoadhesive polymers in vaginal delivery: Advances Drug delivery Reviews 2005: 57, 1692-1712). Nasal drug delivery using mucoadhesive carrier has also been described (Nasal mucoadhesive drug delivery: Background, applications, trends and future perspectives: Ugwoke et al., Advanced Drug Delivery Reviews 2005; 57, 1640-1665).
US application no. 2005/0281775 discloses a method for augmenting an epithelial mucosal barrier by contacting the barrier with a topical composition which comprises a mucoadhesive polymer. The method and compositions discloses are said of being useful in improving mucosal barrier function by, for example, topical application to an exposes or injured epithelial surface or by coating a compromised mucosal barrier in inflammatory bowel disease.